>> Button wants a function in the second argument, which is the function to be> applied to its contents when pressed. This code creates a "pure function"> (look at ref/Function in the documentation center) which ignores the button> contents but assign the value of generate to z.>> On Fri, Nov 15, 2013 at 06:40:37AM -0500, Eduardo M. A. M. Mendes wrote:>> Hello>>>> Many many thanks.>>>> I went through the code you sent me to see if I can understand it. There is one piece that I don't understand. Here is it>>>>>>> (z = generate[\[Lambda], n]) &>>>> Why do I need &? >>>> Thanks again.>>>> Cheers>>>> Ed>>>>>> On Nov 14, 2013, at 8:39 AM, Waclaw Kusnierczyk <waku@idi.ntnu.no> wrote:>>>>> Will this solve your problem:>>>>>> With[{generate =>>> RandomVariate[Quiet@ExponentialDistribution[#1], #2 - 1] &},>>> Module[{z},>>> Manipulate[>>> z = generate[\[Lambda], n];>>> n/Total[z],>>> Button["generate", (z = generate[\[Lambda], n]) &],>>> {{\[Lambda], 2}, 1, 100, 1},>>> {{n, 10000}, 2, 1000000, 1000}]]]>>>>>> Best,>>> vQ>>>>>>>>> On 11/14/2013 08:11 AM, Eduardo M. A. M. Mendes wrote:>>>>>>>> I need to create a simple demonstration based upon an exercise on poisson counting processes. Here is the code>>>>>>>> Manipulate[n/Total[z],Style["Poisson Arrival =Times",18,Bold],"",Delimiter,{{z,Flatten[{0,RandomVariate[Quiet@ExponentialDistribution[\[Lambda]],n-1]}]},Button["random",z=Flatten[{0,RandomVariate[Quiet@ExponentialDistribution[\[Lambda]],n-1]}]]&,Appearance->"Labeled"},"",Delimiter,{{\[Lambda],2,"\[Lambda]"},1,100,1,Appearance->"Labeled"},"",Delimiter,{{n,10000,"n"},1,1000000,1000,Appearance->"Labeled"},SaveDefinitions->True]>>>>>>>> The idea is to generate a sequence of random numbers, then take the sum of it and keep the last value. Every time I hit "random"a new sequence is created.>>>>>>>> The above code returns the following error msg>>>>>>>> RandomVariate::array : "\"The array dimensions -1 + n given in position 2 \>>>> of RandomVariate[ExponentialDistribution[=CE=BB], -1 + n] should be a list of \>>>> non-negative machine-sized integers giving the dimensions for the result. \"">>>>>>>> and some weird output. After hitting "random", the output is what I expect but the whole Manipulate output is still red indicating that there are problems.>>>>>>>> Could you be so kind to point out what I did wrong and how to fix it? I feel that I did not quite get how Manipulate works.>>>>> --> Itai Seggev> Mathematica Algorithms R&D> 217-398-0700